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November 16, 2010

* Acoustic archaeology is an emerging field that melds acoustical analysis and old-fashioned bone-hunting. * Ancient people created fun house-like temples that featured scary sound effects. * Some of the sites were likely built by people who took sensory-altering drugs. The 3,000 year-old Chavin culture produced tunnels and mazes with eerie sound effects.

Researchers are uncovering the secrets of ancient civilizations who built fun house-like temples that may have scared the pants off worshipers with scary sound effects, light shows and perhaps drug-induced psychedelic trips.

The emerging field of acoustic archaeology is a marriage of high-tech acoustic analysis and old-fashioned bone-hunting. The results of this scientific collaboration is an new understanding of cultures who used sound effects as entertainment, religion and a form of political control.

Miriam Kolar, a researcher at Stanford University's Center for Computer Research and Acoustics, has been studying the 3,000 year-old Chavin culture in the high plains of Peru. Kolar and her colleagues have been mapping a maze of underground tunnels, drains and hallways in which echoes don't sound like echoes.

"The structures could be physically disorienting and the acoustic environment is very different than the natural world," Kolar said. Ancient drawings from the Chavin culture show a people who were fascinated with sensory experiences -- ancient hippies if you will.

"The iconography shows people mixed with animal features in altered states of being," said Kolar, who is presenting her recent work at a conference in Cancun, Mexico this week. "There is peyote and mucus trails out of the nose indicative of people using psychoactive plant substances. They were taking drugs and having a hallucinogenic experience."

If that wasn't enough, the mazes at Chavin de Huantar also include air ducts that use sunlight to produce distorted shadows of the maze's human participants. And sound waves from giant marine shells found in the maze in 2001 may have produced a frequency that actually rattled the eyeballs of those peyote-using ancients, Kolar said.

"We consider sound to be important," said Kolar. "We've gathered a lot of data and we're finally starting to publish it."

The Chavin de Huantar site in Peru isn't the only place where sound played an important role. The Mayan rulers at Chichen Itza in the Yucatan also figured out how to use sound for crowd control. David Lubman, an acoustic engineer who has spent the past 12 years studying the Mayan site, says a strange bird-like echo from the Kukulkan temple was actually constructed on purpose.

"It's sort of spooky," Lubman said from Irvine, Calif. "It's not an ordinary echo."

Lubman's analysis compared the acoustic soundprint of the quetzal bird, which was revered by Mayans, to the sound of the echo at Chichen Itza. They two sounds matched.

Lublin said the secret is in the acoustic properties of the steep staircase on the temple's front.

Other new research presented at this week's Acoustical Society of America conference in Cancun shows that Mayan rulers figured out how to build a public address system in the site's giant ball court. That allowed kings to address hundreds of warriors and subjects without screaming.

In England, British researchers are using modern tools of acoustics to figure out what drumming noises may have sounded like to ancient visitors to Stonehenge.